In recent years, toners have been required to exhibit an excellent fixing property and have a smaller particle size from the viewpoint of achieving higher image qualities. As resin binders for the toners, there are known styrene-acrylic resins, polyesters, etc. In particular, the polyesters have been used because of excellent durability and fixing property thereof. As such a polyester, there has been disclosed the polyester containing an alkyl succinic acid and/or an alkenyl succinic acid having 10 or more carbon atoms as a carboxylic acid component thereof, in particular, in view of a good fixing property, and there has also been disclosed the toner using the polyester as a resin binder which is produced by a melt-kneading and pulverizing method (refer to JP 57-109825A and JP 2000-35695A). However, when a toner having a small particle size and using a resin binder containing a polyester as a main component is produced by the melt-kneading and pulverizing method, it tends to be difficult to control a particle size of the toner upon pulverization.
On the other hand, JP 2004-198598A discloses a process for producing a toner by an emulsification and aggregation method as a wet process.
However, when a toner containing a polyester as a resin binder is produced by the wet process, an ester bond of the polyester tends to be hydrolyzed in a solution. As a result, the obtained toner tends to exhibit a low glass transition point and therefore tends to be deteriorated in storage stability and fixing property.